Abstract: Strip foundation of concrete is traditionally used in Denmark where it is placed 0.9 m underneath the finished ground surface to reach stable non-freezing ground. New prefabricated lightweight elements used as strip foundation placed on the stable ground underneath the top soil layer, just 0.3 m underneath the finished ground surface, have been introduced and demonstrated as an alternative. The prefabricated elements, made of expanded polystyrene (EPS), can be used as the strip foundation of a house of up to two storeys. The EPS element has been designed to comply with the new revised Danish Building Regulations and allow very little energy to be lost through the foundation element combining the concrete slab and the outer wall. The EPS element has been specially designed to form the base of a traditional double-brick wall, a traditional wood-stud wall, and combinations of lightweight concrete, brick and wood-stud walls within/separated by insulation. This paper demonstrates the use of the introduced prefabricated EPS element used as strip foundation forming the base of a traditional single-family house. The house is a one storey house with an exterior wall made as a double-brick wall separated by insulation. The design criteria for the EPS element will be outlined and methods to establish stable non-freezing ground underneath the EPS element will be described. Furthermore it will be shown how the EPS element is handled on site. The paper will demonstrate two-dimensional finite difference calculations of the temperature underneath the foundation. Calculations will be compared with temperature measurements taken on site, at measurement points located along lines from under the strip foundation at the outer plinth and in continuation of these points underneath the building. In addition the soil temperature and temperature and relative humidity indoors and outdoors will be measured. Measurements cover the construction period as well as a period after completion.